这项计划有什么优势?What's the advantage of this plan?1).安全2).价格更低3)准备时间短_?Orbital Space Plane4
When the moon crosses the ecliptic — Earth's orbital plane — it is known as a lunar node. The distance at which the new moon approaches a node will determine the type of solar eclipse. The type of solar eclipse is also affected by the moon's distance from Earth and the distance betw...
After the sky fully darkens in early January, the Andromeda Galaxy is positioned near the zenith (the highest point in the sky directly above an observer), which is ideal for viewing it through a minimum of Earth's atmosphere. The galaxy will descend the western sky as the hours roll by...
Getting there is a slog! Starting at the Sun, there’s a 93-million-mile commute to Earth. Much farther than that and it stops making sense to measure in miles. Astronomers use that 93-million-mile distance, the average orbital distance of the Earth, as a unit of distance called an ...
But the moon also happens to be about 400 times closer to Earth than the sun is (the ratio varies as the orbits of both the sun and moon are elliptical); and as a result, when the orbital planes intersect and the distances align favorably, the moon (called a "new moon" in this ...